An important genetic risk factor for the development of alcoholism is differential sensitivity to an acute dose of alcohol. Using segregating populations derived from selectively bred rat lines, we have mapped quantitative trait loci (QTLs) on rat chromosomes 1 and 2 for an acute response to alcohol, the duration of the loss of righting reflex (LORR). We have subsequently generated congenic and recombinant congenic lines that have confirmed the QTLs while simultaneously reducing their genomic size. We hypothesize that there are one or more genes within the QTL intervals that contribute to genetic variance for LORR through polymorphism- related effects on gene expression and/or on the structure of the genes' products. A second important hypothesis is that these same genes will influence genetic variance in alcohol reward-related behaviors. To address these hypotheses, the project will carry out four Specific Aims: 1) Fine-map the chromosome 1 and 2 QTLs using the recombinant congenic strategy; 2) Identify candidate genes in the fine-mapped areas of the chromosome 1 and 2 QTLs; 3) Identify enriched functional pathways and gene networks that are affected by the QTLs; and 4) Determine if the chromosome 1 and 2 QTLs are pleiotropic with alcohol reward-related behaviors. Contemporary genetic and genomic methods and analytical approaches, including high-throughput DNA and RNA sequencing, will be used to accomplish the goals of the Aims. We propose that the results of these experiments will offer insight into the nature of genetic variance for acute alcohol sensitivity. This in turn will contribute to a deeper understanding of genetic risk for human alcoholism.